Understanding Cable Markings
Cable from a laptop power supply supplying 12Vdc at 2A over 1 meter. Text on the cable: E157914 PRIMAX RU AWM 1185 80 degC 300V VW-1 CSA LL110529 AWM I A/B 80 degC 300V 18AWG FT1 LM
The text on the cable tells us a lot about the cable but most of it is cryptic. We can tell straight off this is 18AWG cable (about 0.75mm^2) and that it’s good for 300V at 80degC. After that though a little more detective work is required.
AWM stands for Appliance Wiring Material and is a standard category of wire and cable. AWM cables are using in just about everything including general purpose wiring circuits, control circuits and internal wiring of appliances. Underwriters Laboratory (UL) categorises AWM as a recognized component used in listed or classified products and provides a searchable database of data about the variously certified cables, for example here is the cable given in the example above.
The 1185 after the AWM is the style code which can be searched on directly to get extra information about the cable (use the style page search). You can also search on the code beginning with an E (in this case E157914). This, I believe, is the code of the company that made the cable which in this case is Primax. For this cable at least the code doesn’t directly turn up a company, the cable is a few years of so I imagine the company has gone out of business. If you use a parametric search based on the E157914 code you can find the cable so it seems UL still know something about the company that made it.
The VW-1 and FT1 both mean that the outer jacket of the cable is fire retardant, there are differences in the meanings but basically they won’t spontaneously catch fire and burn your house down.
The “CSA LL110529” code is for the Canadian Standard Association, the Canadian version of UL. The number after is a file number so you can look up the cable.
I A/B, anyone’s guess
LM, also anyone’s guess
Finding Cable for the LED’s
One of the hardest parts of this project turned out to be finding cable suitable for the 2.1 mm power jacks that I use to connect the LED strips to the distribution boxes. Suitable cable is absolutely everywhere (for example every laptop power supply has suitable cable running from the brick to the laptop) but despite searching high and low I couldn’t find anywhere that sold it, I even asked on EEVBlog but got no replies. Digikey got the closest but the cable was grey and I wanted black to match the jacks, Farnell weren’t even close and RS could supply something that would work if necessary. The specification I was looking for was 18AWG or 0.75mm^2 with an outer diameter of 4.9 to 5.1mm (5.0 ideal) and preferably black – sounds like it should be simple doesn’t it.
With this cable being so hard to find I was ready for open wallet surgery when I did find some. I eventually found a supplier on Alibaba but, of course, they had a minimum quantity of 1000 meters and I probably need about 5 meters. Eventually I made my way back to eBay (I’d already tried and failed several times there) and guess what, I hit the jackpot. If you search for “laptop power supply extension cable” or “DC Power Supply Extension Cable” or something like that you’ll find a reasonable number of pre-made cables with 2.1 mm jacks. Turns out this cable is used for powering CCTV cameras amongst other things. In the end I managed to get 10 meters for less than £4 shipped.